Surgical screws and pins used in the fixation of bone fractures and separations occurring in humans and in animals are well known in the art. The medical devices and methods known heretofore, however, are poorly suited for treating fractures and separations of small bones or for treating those fractures and separations resulting in small bone fragments. These types of injuries require more than a simple downsizing of existing equipment.
A common problem encountered when two or more bones are to be joined together after a break or fracture is that they must be positioned properly relative to each other. The surgeon accomplishes this by first maneuvering the bones into the relative position he or she believes to be proper and then inserts a first pin or screw. If the bones are not positioned properly the pin (or screw) must be removed and a new hole drilled. This second hole is close to the first, particularly in small bones, and thus often slips because the hole in the bone is elongated. Thus, often it is necessary to position a second hole very close to a first hole without the two holes overlapping and with the holes having a fixed and measurable positional relationship with each other.
A second problem is that when a pin is used for the initial stabilization it is often necessary to lock that pin in place such that at a future time the pin can be easily removable.
One such device is disclosed in U.S. Pat. No. 4,360,012 to McHarrie et al. This prior art discloses a large orthopedic fixture for drilling parallel bores through a long straight bone. A guide is attached to a elongate member and allows a drill bit to be aligned along a known direction. The guide may be repositioned along the elongate member to create other holes. The size of the device makes it particularly ill-suited for the repair of small bone breaks. Small bone fragments are often smaller than the disclosed guide itself. Also, the device does not address how the fractured bone is temporarily held in place while the first bore is drilled. Maintaining the desired alignment between the bone fragment and the underlying bone mass while drilling a hole in a surgical setting can be difficult, to say the least.
U.S. Pat. No. 4,037,592 to Kronner discloses a guide pin locating tool and method. The disclosed device is intended for use in repairing a separation of the femoral shank from the femur. The tool is temporarily attached to the base of the femur with a pin inserted into the bone. A drill guide is attached to the base and pivots in two axes for precise alignment prior to drilling. Again, this prior art does not lend itself generally to small bone breaks. The guide is large and requires a large surgical incision along the femur to accommodate its use. The guide requires the insertion of a pin (for attachment of the base) that ultimately does not strengthen the break. The tool also fails to provide a means for preventing the bone fragment from rotating about the axis containing the inserted pin. A bone fragment may spin about a single pin if the fracture occurs predominantly along a single plane.
U.S. Pat. No. 4,608,972 to Small discloses a method of applying a chin implant, drill guide tool and implant. This prior art attaches a chin implant to the human mandible with two screws. The screws are laterally spaced by two channels within the guide. The device itself is aligned on the jaw with a third channel by a temporary pin inserted into the jaw. Although this device provides positive counter-rotational means, it does so at the expense of size, inflexibility and complexity. The guide uses two relatively large screws separated by an invariable distance positioned by an alignment pin that is immediately removed and discarded. The method is not suited to growing bones. In such circumstances, bone growth under the had of each screw would damage the growth of the bone.
U.S. Pat. No. 4,754,749 to Tsou discloses a surgical screw with counter-rotation prevention means. Here a surgical pin is inserted through a channel machined into the head of the installed screw nd into the underlying bone mass. The screw and pin form an acute angle. The disclosed device does not indicate how the screw is initially aligned relative to the bone nor how the alignment is maintained during drilling of the hole.
Therefore, a need has arisen in the art for a drill guide and method that is suitable for the repair of small bone breaks and which provides a positive means for aligning the bone piece and underlying bone mass during drilling.
A further need exists in the art for such a guide having a counter-rotational means to prevent the bone fragment and screw from rotating relative to the underling bone mass.
A still further need exists in the art for such a guide that is adaptable to fractures or separation in growing bones.
A still further need exists in the art for bone stabilization method and device which allows for holes to be drilled parallel to each other and in close proximity to each other.
A still further needs exists in the art for such a device and method which allows for multiple holes to be drilled in a bone, all spaced in relative close proximation to each other and all having a controlled angle of bone penetration.
A still further need exists in the art for a device and method of bone stabilization which allows for the selective locking and releasing of adjacent stabilizing pins.